Did you never have problems with shifts in z direction? I tried a flexible coupler on my UMO once and then immediately removed it again.

No.

Though bought a used Hictop an they shipped it assembled sort of.
They removed the top Aluminum Frame an laid into a box loosely with the steppers still attached to the couplers and lead screws.
You probably figured out the couplers were stretched beyond belief, could not help but LOL when I saw your couplers, as it reminded me of this.

Last edited by Roberts_Clif on August 1st, 2017, 2:40 pm, edited 1 time in total.

They also suggest making sure everything is aligned, checking that the z screw lines up with the stepper. Some use a spacer to adjust the motor over a bit. I am not sure if this happens in shipping, from being banged around....or poor quality control.

It really doesn't take a rocket scientist to tell that using a flexible coupling there is a really bad idea. I'd also recommend an Oldham coupler similar to the one you found there on Amazon. Personally, I'd go with a quality brand product, but these things can be quite expensive (Misumi Oldham couplings cost 15+ EUR, and that's the "cheap" ones with grub screws instead of the clamping design).